100 Orthonhapha biachycera. 



when at rest they are borne nearly parallel, in a somewhat roof- 

 shaped way. 



According to Brauer (Denkschr. d. kais. Akad. d. Wissensch. XLVII, 

 42, TalD. II, Fig. 35—37, Tab. III, Fig. 38—40) the larva is cylindric. 

 longitudinally Ptriated, white, on the dorsal side witli a design of 

 greyish brovvn spots, caused by microscopic hairs. The body consists 

 of twelve segments in all. On the ventral side tliere are several trans- 

 verse swellings with small spines (Kriechschwielen) : fonrth to tenth 

 segments (when the head is included fifth to eleventh) have each two 

 spined swellings on the dorsal surface. The last segment has tlie 

 anus on the ventral side, between a pair of swoUen lips, and it bears on 

 the end a conical, retractile process, with a vertical split in the apex, 

 leading to the tracheæ; the larva is metapneustic. The mouth parts 

 consist of a vertical iabrum, hookformed mandibles with the convex 

 front edge transversely furrowed and hence serrated. and maxillæ 

 which are less chitinised, with two-jointed palpi; on each side at the 

 base of the labrum there is a piece, beset with two-pointed spines, 

 bearing the antennæ, which are two-jointed; the apical joint is longi- 

 tudinally cleft in two parts, (I think the faet is, that there is besides 

 the apical joint a process placed on the first joint). On each side 

 of the head there is an eye-spot. The pupa has two tubercJes above 

 the base of the antennal sheaths, each with a bristle, (these may be 

 the same tubercles, which in Chrijsops bear two bristles, but in 

 Hæmatopota and Tabanus one; the faet is not distinctly seen in 

 Brauer's descrlption), and sonie more small tubercles above and below. 

 The prothoracic spiracles are placed on low, cylindrical protuberances. 

 The larva lives in water. the pupa in the earth. 



The single species, which on account of the northern position is 

 very rare here, is said to be very bloodthirsty; it is especially found 

 in the vicinity of water. 



The genus only includes one species. 



1. H. pellucens Fabr. 



177C. Tahanus, Fabr. Gen. ins. Maiitiss. 307. — 1862. Schin. F. A. 

 I, 37. — 1903. Kat. palaarkt. Dipl. 11, 54. — 1848. H. bimaculata Wahl- 

 berg, Ofvers. Kgl. Vet. Akad. Ftirli. V, 198. 



Male. Eyes with two bluish bands below the part with the large 

 facets. Face and palpi dark brown with grey hairs. Thorax black, 

 pubescence yellow, grey beneath. Abdomen black, shining somewhat 

 bluish, on the second segment with a bluish white, pruinose spot on 

 each side, which is most distinctly seen, when the light falls in from 

 behind. Venter blackish with bluisli white transverse spots on each 



